Semiconductor packaging is accomplished by forcing a molding material, usually a plastic or plastic epoxy, into a mold to cover the semiconductor circuitry. The plastic is very hard but when initially heated, becomes quite malleable allowing the plastic to be forced into the mold.
The plastic molding material is usually shipped to the packaging plants in pellet form, often looking similar to hockey pucks. Several of these pellets are placed into a container which is connected to the packaging mold. An orifice or small opening joins the container and the packaging mold to allow the heated plastic to be forced from the container into the mold.
The container is heated to soften the pellets into malleable material. Once the material has been softened sufficiently, a press mechanism is inserted into the container to force the plastic into the mold.
One of the problems associated with this process is the presence of air pockets which are trapped within the plastic and flow with the plastic into the mold. As the plastic cools, the entire packaging hardens and these air pockets form voids within the semiconductor chip package. Such voids allow the circuitry pad to corrode and causes package delamination. The obvious result is rejection of the part by the manufacturer's customer and reduction in product yield.
Therefore, it would be advantageous to have an apparatus and method which eliminated the air trapped within the plastic during the molding process to avoid air pockets and eventual corrosive voids.